When traveling, one generally doesn't care as much about the distance to a destination as much as the time it takes to get there. When planning travels, it is difficult to plan stops in advance since so many parameters affecting speed are unavailable on a standard map or global positioning system (GPS) device. In a wilderness situation, it may be critical to know if a road or help can be reached before sunset. It may be better to spend remaining daylight hours building shelter for the night instead of pushing on to unreachable help. Current maps and GPS devices are very good at calculating distances and showing elevations, but are incapable of translating that information into travel time.